Detachable clamp with a leaf spring

ABSTRACT

The disengageable clamp of a cable car or chair lift has a control lever  17  carrying the movable jaw  14 , articulated on the fixed jaw  13 . At least one flexion leaf spring  23  is interposed between the clamp body  10  and the control lever  17  in order to force this lever into the clamp closure position. Two leaf springs can be disposed on each side of the clamp body  10.

The invention relates to a disengageable clamp for coupling a load to atrack/traction cable for an overhead cable transportation installation,comprising a clamp body extending transversely on one side of the body,in a position coupled to the latter, and carrying an articulation of asuspension member supporting the load, a cable clamping vice, consistingof a fixed jaw carried by the clamp body and a movable jaw articulatedon the fixed jaw, a control lever, which is integral with the movablejaw and extends the latter whilst lying and travelling in a planeperpendicular to the cable and containing the clamp body, in order tocontrol the opening and closing of the vice, and at least one springacting on the control lever in the closed position of the jaw.

BACKGROUND OF THE INVENTION

1. Discussion of Prior Art

A known clamp of the type mentioned (EP-A-0 056 919) has coil springsinterposed between the clamp body and the control lever. The coilsprings require an axial guide rod and articulations in the springanchoring areas. This arrangement is complicated and the springs have alarge amount of travel and are therefore bulky.

The aim of the present invention is to permit the production of adisengageable clamp with a simple and compact structure, insensitive tofrost and ice, so as to be able to remain on line permanently.

The clamp according to the invention is characterised in that the springis a flexion leaf spring, which cooperates on the one hand with thecontrol lever and on the other hand with the clamp body, the leaf springextending substantially in the said plane or parallel to this plane andin the general direction of the clamp body, and supplying the force forcoupling the clamp to the cable.

A leaf spring can be housed in a restricted space and there is no riskof it being blocked by ice, the latter breaking under the least flexionof the spring. The absence of a guide rod also reduces the risk ofblocking. The leaf of the spring can have, at rest, various shapes and,through a judicious choice of the anchoring points and/or of theconfiguration and structure of the leaf, it is easy to obtain a suitablecurve for the variation in the clamp control force. The spring can be ofa well known type with several leaves placed one on top of the other,with different characteristics.

The document WO-A-87 01081 and the document DE-B-10 80 580 discloseclamps incorporating a leaf spring, but this spring does not supply theforce for coupling to the cable, which is derived from the weight of thecar.

2. General Discussion of the Invention

According to a development of the invention, two springs are disposedsymmetrically on each side of the plane containing the clamp body andcontrol lever, so as to ensure the security of coupling of the clamp tothe cable in the event of breakage of one of the springs and so as todistribute the forces.

According to one embodiment of the invention, the spring leaf, ofelongate shape, is interposed between the clamp body and the controllever, one of the ends being, for example, anchored rigidly to the clampbody, on the same side as the vice, and the other end cooperating with aroller carried by the control lever, on the same side as the free end ofthe latter. The leaf thus extends almost parallel to the control leverand releases the space around the clamp body in the suspension memberarticulation area.

According to a variant embodiment, the leaf spring is almost straight,in the position of clamping the clamp, and is fixed at both ends, so asto be subjected to a buckling force during the opening movement of theclamp. The opening control is exerted on the control lever, in the usualfashion, or preferably directly on the spring.

According to another embodiment, the leaf spring has an appreciablecurvature, for example in the form of a half loop or several loops in adrum shape, with a view to increasing the length of the leaf whilstlimiting the bulk.

The ends of the spring leaf can be anchored rigidly, for example byembedding, on the clamp body and/or on the control lever, or can have anarticulation allowing a limited relative movement.

According to another embodiment of the invention, the leaf spring isbuttressed by its ends on the clamp body and its middle part cooperateswith the control lever, a reverse arrangement being possible. One of theends of the spring is, for example, embedded on the clamp body, whilstthe opposite end is mounted for limited sliding by means of a rocker bararticulated on the clamp body. The two supports can consist ofarticulated rocker bars. The middle part of the spring is in abutment ona lug carried by the control lever in order to transmit the force of thespring to this lever. Two buttress springs with opposite curvatures canbe associated by connecting their respective ends, the middle part ofone of the springs cooperating with the control lever and that of theother spring with the clamp body. The ends of the springs are perfectlyconnected by articulations and, in this case, at least one of the middleparts is rigidly anchored to the clamp body and/or control lever.

Other advantages and characteristics will emerge more clearly from thefollowing description of various embodiments of the invention given byway of examples and depicted in the accompanying drawings, in which:

DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are schematic elevation views of a clamp according to theinvention, depicted respectively in the open position and in the closedposition;

FIGS. 3 and 4 are views similar to FIG. 1 showing two differentarrangements of the springs;

FIGS. 5 and 6, 7 and 8, 10 and 11 are views similar to FIGS. 1 and 2,illustrating three variant embodiments according to the invention;

FIG. 9 is a plan view of the clamp according to FIG. 1;

FIG. 12, similar to FIG. 10, shows a spring consisting of two combinedleaves;

FIG. 13 is a view similar to that of FIG. 11, showing a differentarrangement of the spring;

FIGS. 14 and 15 are views similar to FIGS. 1 and 2, illustrating amethod of controlling the clamp by direct action on the spring;

FIGS. 16 and 17, 18 and 19 are views similar to FIGS. 1 and 2, showingtwo embodiments of the invention, using buttressed springs.

DETAILED DESCRIPTION OF THE INVENTION

In all the figures the same reference numbers are used to designatesimilar or identical parts. A disengageable clamp has an elongate body10 which extends, in the position where the clamp is coupled to thecable, transversely to the cable. The body 10 carries an articulation 11for a suspension member 12 and is extended by a pair of jaws 13, 14forming a cable clamping vice. One 13 of the jaws is fixed and the otherone 14, which is movable, is articulated on a shaft 15 carried by thebody 10. In the position of clamping of the cable by the jaws 13, 14,the shaft 15 extends parallel above the cable. The movable jaw 14 isformed at the end 16 of a control lever 17, which extends and cantravel, when pivoting on the shaft 15, in a plane perpendicular to thecable, which contains the clamp body 10 and which corresponds to theplane of FIG. 1. At the end 18, opposite the movable jaw 14, of thelever 17 there is fixed a rotation shaft 19 for a control wheel 20, ableto cooperate with a control rail 28. The clamp body 10 carries bearingrollers 21 and a cross member 22 for driving by friction, in order tomove the clamp, disengaged from the cable, in the stations on transferrails. Such a clamp is well known and it is unnecessary to describe itin any further detail.

Referring particularly to FIGS. 1, 2 and 9, it can be seen that thecontrol lever 17 is acted on in the cable clamping position by a pair ofleaf springs 23, 24 interposed between the control lever 17 and theclamp body 10. The two springs 23, 24 are disposed symmetrically on eachside of the plane defined by the control lever 17 and the clamp body 10and extend parallel to this plane in the general direction of thecontrol lever 17. One 25 of the ends of the springs 23, 24 is rigidlyanchored by embedding in the clamp body 10 on the same side as the jaws13, 14 whilst the opposite end 26 bears on a roller 27, mounted forrotation on the controller lever 17 on the same side as the controlwheel 20. In the closed position of the clamp, depicted in FIG. 2, theleaf springs 23, 24 are substantially straight, under pretension, andexert a force F on the control lever 17, tending to pivot the latter inthe counter clockwise direction, for clamping the cable. When thecontrol rail 28 moves the control wheel 20 downwards, the control lever17 pivots in a clockwise direction towards the position, depicted inFIG. 1, of opening of the clamp, counter to the force F′ exerted by thesprings 23, 24, curved downwards. It should be noted that thisarrangement of the springs 23, 24 completely releases the space aroundthe articulation 11 of the suspension member 12. The roller 27 canconsist of a single stop or conversely have a guide runner for the end26 of the spring. It is clear that the roller 27 can be disposed on theclamp body 10, the spring 23, 24 then being embedded on the controllever 17, and that the clamp can have a single spring or conversely alarger number of springs.

FIG. 3 illustrates a variant in which the springs 23, 24 are embedded onthe side of the clamp body 10 opposite to the jaws 13, 14, while theirfree end 26 is in abutment on a roller 27 disposed on the middle part ofthe control lever 17. The functioning of the clamp is not changed, butit should be noted, that, in the arrangement of the springs 23, 24according to FIGS. 1 and 2, the lever arm of the forces F and F′ remainssubstantially constant, while in the arrangement according to FIG. 3 thelever arm varies appreciably.

In the embodiment depicted in FIG. 4, the springs 23, 24 are bent in theform of a half-loop, one end of which 25 is embedded on the clamp body10, on the side opposite the jaws 13, 14, and the other end 26 of whichis embedded on the control lever 17 on the same side as the wheel 20.The great length and the bent shape of the spring leaf 23, 24 allowcompensation for the relative movement of the anchoring points, and theleaf can be embedded at both ends, which simplifies the assembly.

The embodiment illustrated by FIGS. 5 and 6 repeats the arrangementaccording to FIGS. 1 and 2, with the abutment of the spring 23, 24 onrollers 27 on the same side as the roller 20 of the control lever 17 andembedding on the clamp body 10 on the same side as the jaws 13, 14, butthe embedding point is shifted upwards level with the cross member 22.In this case, the lever arm of the force F′ of the open clamp is lowerthan that of the force F of the closed clamp and the control force forthe clamp can thus be maintained substantially constant or even reducedas the clamp opens. It will be understood that a judicious choice of thecharacteristics of the springs 23, 24 and of the anchoring points makesit possible to obtain the required curve for the variation in clampcontrol force.

Referring to FIGS. 7 and 8, it can be seen that the springs 23, 24 arecoiled in a drum shape, in the form of a clothes peg spring, one 25 ofthe ends of the springs 23, 24 being articulated on the clamp body 10,whilst the opposite end 26 is articulated on the control lever 17 on thesame side as the control wheel 20. In the closed position of the clamp,depicted in FIG. 8, the springs 23, 24 are under pre-tension and exert aforce on the control lever 17, tending to pivot the latter in thecounter clockwise direction, for clamping of the cable. It should benoted that one or both ends 25, 26 can be embedded. With each spring 23,24 there can be associated a conjugate spring 23′, depicted in brokenlines in FIGS. 7 and 8. The conjugate spring 23′ has the same shape andis articulated at the same points as the associated spring, but isarranged opposite and its direction of coiling is the contrary. In thisway the restoring force and the security of the clamp are increased.

In FIGS. 10 and 11, the springs 23, 24, of elongate shape, aresubstantially straight, under pre-tension and slightly precurved, in theposition of closure of the clamp, depicted in FIG. 11. They exert aforce F on the control lever 17, tending to pivot the latter in thecounter clockwise direction, for clamping the cable. When the controlrail 28 moves the control wheel 20 downwards, the control lever 7 pivotsin the clockwise direction towards the position, depicted in FIG. 10, ofopening of the clamp, causing the springs 23, 24 to flex by buckling.The force opposed by the springs 23, 24 remains substantially constantfrom the very start of the buckling, which makes it possible to limitthe control energy. The articulation of the ends 25, 26 of the springs23, 24 consist, for example, of a simple bending of these ends in a looparound a pivot carried by the control lever 17 or clamp body 10. One orboth ends 25, 26 of the springs 23, 24 can be embedded. The springs 23,24 can be precurved on one side or the other, and it is advantageous toassociate, with each spring 23, 24, a conjugate spring 23′, of oppositecurvature, and articulated at the same points, in order to constitutepairs of springs, 23, 23′ in the form of an ellipse, as depicted in FIG.12, in order to double the force and increase security.

According to the variant illustrated by FIG. 13, the springs 23, 24 arearticulated in the vicinity of the ends of the lever 17 and clamp body10, the point of fixing to the clamp body 10 advantageously beingshifted downwards by means of an appendage 31, so as to elongate thesprings 23, 24 and to adapt their characteristics.

FIGS. 14 and 15 illustrate another method of controlling the clamp. Themovable jaw 14 of the clamp is carried by a shortened lever 29, on whichone 25 of the ends of the spring 23, 24 is articulated, the other end 26is articulated on the shortened lever 29 on the opposite side to thejaws 13, 14. In its middle part the spring 23, 24 carries a loose wheel30, able to cooperate with the control rail 28, extending along the pathof movement of the clamp, in order to cause the spring 23, 24 to buckleand the jaws 13, 14 to open. The buckling force on the spring 23, 24 canobviously be applied to the spring 23, 24 in any other operative manner,notably by means of shoes. Such a clamp is particularly simple and it isclear that the spring 23, 24 can be disposed differently, notablyaccording to one of the variants described above.

The method by which the flexion leaf springs 23, 24 work is different inthe embodiments depicted in FIGS. 16 to 19. In the clamp according toFIGS. 18, 19, one 25 of the ends of the springs 23, 24 is anchoredrigidly by embedding in the clamp body 10 on the same side as the jaws13 and 14, whilst the opposite end 26 is articulated on a rocker bar 34,the opposite end of which is articulated on the clamp body 10. Themiddle part of the springs 23, 24 is loaded by a roller 27 carried bythe control lever 17. In the closed position of the clamp, depicted inFIG. 19, the leaf springs 23, 24 are curved under pre-tension and exerta force on the control lever 17, tending to pivot the latter in thecounter clockwise direction, for clamping the cable. When the controlrail 28 moves the control wheel 20 downwards, the control lever 17pivots in a clockwise direction towards the position, depicted in FIG.18, of opening of the clamp, counter to the force F exerted by thesprings 23, 24. It is clear that the roller 27 can be disposed on theclamp body 10, the springs 23, 24 then being fixed, in abutment throughtheir two ends, to the control lever 17 with an opposite curvature.

FIGS. 16 and 17 illustrate a variant, in which each spring 23, 24 isassociated with a conjugate spring 23′ with an opposite curvature, eachend 25, 26 and the spring 23, 24 being connected by an articulation 32,33 to a conjugate end 25′, 26′ of the associated spring 23′, in order toconstitute a pair of springs of elliptical shape. The middle part of thespring 23, 24 cooperates with the control lever 17, while the middlepart of the conjugate spring 23′ cooperates with the clamp body 10.These middle parts can be fixed rigidly, for example by embedding, or bearticulated on the clamp body 10 and/or control unit 17. They can alsobe in abutment on a roller carried by the control lever 17 and/or clampbody 10, in a manner similar to that described above, the positioning ofthe conjugate springs 23, 23′ being in this case provided by anyeffective means, for example by mounting the articulation 32 forrotation on a shaft carried by the clamp body 10, as depicted in FIGS.16 and 17.

Arrangements, notably for fixing the springs, described in detail in oneof the above examples are of course applicable to the other examples.

What is claimed is:
 1. A disengageable clamp for coupling a load to atrack/traction cable for an overhead cable transportation installation,said clamp consisting essentially of: a clamp body having a transverseextension coupled on one side of the body, and carrying an articulationof a suspension member for supporting the load, a cable clamping viceconsisting of a fixed jaw carried by the clamp body and a movable jawarticulated on the fixed jaw, a control lever integral with the movablejaw and extends from the movable jaw for lying and moving in a plane, inorder to control opening and closing of the vice, and at least onespring exerting a force on the control lever in the closed position ofthe jaw, wherein said spring is a flexion leaf spring in contact withthe control lever and with the clamp body, said leaf spring extendingsubstantially parallel to said plane, and being capable of supplying aforce for coupling the clamp to the cable.
 2. The clamp of claim 1,wherein one of the ends of the leaf spring is rigidly anchored to theclamp body, and the other end is in contact with the control lever,allowing a limited relative movement.
 3. The clamp of claim 1, whereinone of the ends of the leaf spring is rigidly anchored to the controllever, and the other end is in contact with the clamp body, allowing alimited relative movement.
 4. The clamp of claim 1, wherein the leafspring is in the form of a half-loop, one of the ends which is anchoredon the clamp body on the side opposite the jaws, and the other end ofwhich is anchored to the control lever on a side on which is located acontrol wheel.
 5. The clamp of claim 1, wherein the leaf spring is inthe form of a clothes-peg spring, having a part coiled in a drum shape,the turns of which lie in planes parallel to said plane.
 6. The clamp ofclaim 1, wherein the leaf spring is fixed to the clamp body and to thecontrol lever in order to be loaded at an end thereof, while being in analmost straight position on closing of the jaws and in a buckledposition on opening of the jaws.
 7. A disengageable clamp for coupling aload to a track/traction cable for an overhead cable transportationinstallation, said clamp comprising: a clamp body having a transverseextension coupled on one side of the body, and carrying an articulationof a suspension member for supporting the load, a cable clamping viceconsisting of a fixed jaw carried by the clamp body and a movable jawarticulated on the fixed jaw, a control lever integral with the movablejaw and extends from the movable jaw for lying and moving in a plane, inorder to control opening and closing of the vice, and at least onespring exerting a force on the control lever in the closed position ofthe jaw, wherein said spring is a flexion leaf spring in contact withthe control lever and with the clamp body, said leaf spring (1)extending substantially parallel to said plane, (2) being capable ofsupplying a force for coupling the clamp to the cable, (3) beingbuttressed through an end on the clamp body or control lever, and (4)being in contact, through a middle part thereof, with the control leveror clamp body.
 8. The clamp of claim 7, wherein one of the ends of thespring is rigidly anchored, while the opposite end is articulated on arocker bar with an articulated connection.
 9. A disengageable clamp forcoupling a load to a track/traction cable for an overhead cabletransportation installation, said clamp comprising: a clamp body havinga transverse extension coupled on one side of the body, and carrying anarticulation of a suspension member for supporting the load, a cableclamping vice consisting of a fixed jaw carried by the clamp body and amovable jaw articulated on the fixed jaw, a control lever integral withthe movable jaw and extends from the movable jaw for lying and moving ina plane, in order to control opening and closing of the vice, and atleast one spring exerting a force on the control lever in the closedposition of the jaw, wherein said spring is a flexion leaf spring incontact with the control lever and with the clamp body, said leaf spring(1) extending substantially parallel to said plane, (2) being capable ofsupplying a force for coupling the clamp to the cable, (3) being fixedto the clamp body and to the control lever in order to be loaded at anend thereof while being in an almost straight position on closing of thejaws and in a buckled position on opening of the jaws, and (4) carryingin a middle part thereof a control piece to come into contact with acontrol rail extending along a movement path of the clamp, in order tocause buckling of the spring and opening of the jaws.
 10. Adisengageable clamp for coupling a load to a track/traction cable for anoverhead cable transportation installation, said clamp comprising: aclamp body having a transverse extension coupled on one side of thebody, and carrying an articulation of a suspension member for supportingthe load, a cable clamping vice consisting of a fixed jaw carried by theclamp body and a movable jaw articulated on the fixed jaw, a controllever integral with the movable jaw and extends from the movable jaw forlying and moving in a plane, in order to control opening and closing ofthe vice, and at least one spring exerting a force on the control leverin the closed position of the jaw, wherein said spring is a flexion leafspring system in contact with the control lever and with the clamp body,said leaf spring system (1) extending substantially parallel to saidplane, (2) being capable of supplying a force for coupling the clamp tothe cable, (3) comprising two leaf springs having opposite curvaturesassociated by links articulated at their ends, forming a buttressedspring in an ellipse, and (4) having a middle part of one of the leafsprings cooperating with the clamp body and a middle part of the otherleaf spring cooperating with the control lever.
 11. A disengageableclamp for coupling a load to a track/traction cable for an overheadcable transportation installation, said clamp comprising: a clamp bodyhaving a transverse extension coupled on one side of the body, andcarrying an articulation of a suspension member for supporting the load,a cable clamping vice consisting of a fixed jaw carried by the clampbody and a movable jaw articulated on the fixed jaw, a control leverintegral with the movable jaw and extends from the movable jaw for lyingand moving in a plane, in order to control opening and closing of thevice, and at least one spring exerting a force on the control lever inthe closed position of the jaw, wherein said spring is a flexion leafspring system in contact with the control lever and with the clamp body,said leaf spring system (1) extending substantially parallel to saidplane, (2) being capable of supplying a force for coupling the clamp tothe cable, and (3) comprising two leaf springs that are disposedsymmetrically on another plane perpendicular to said plane in which theclamp body and the control lever are located, so as to ensure securityof coupling of the clamp to the cable and to distribute clamping forces.